Bash – Difference Between .bashrc and .inputrc

bashbashrcinputrcshell-script

I am new to the unix system, and find it interesting to create customized functions and configurations in the setting files like .bashrc and .inputrc.

However, I don't understand the differences between the two. For example, when I created alias, I put them in .bashrc.

Example 1: alias ...='cd ../../'

When I create operations like using arrow key to look for previous or next command, I put the command in .inputrc.

Example 2: "\e[A": history-search-backward

Why I need to put them in different setting files? How do I distinguish when to put what where?

Thank you in advance!

Best Answer

Settings that are in the .inputrc file affect all programs that use the GNU readline library, not just bash. Think of the .inputrc file as being a configuration file for GNU Readline similar to how .bashrc is a configuration file for bash.

GNU Readline is described as:

... A set of functions for use by applications that allow users to edit command lines as they are typed in.

To clarify a bit further, settings that are in the .bashrc file only affect bash. If you'd like to optionally run bash without GNU Readline support or usage, you can invoke bash with the --noediting option as follows: bash --noediting. You can find out more about bash options here.

To answer your last question of

How do I distinguish when to put what where?

If you'd like an option to affect all programs on your system that use the GNU Readline library, .inputrc would be the prime choice. Elsewise, if you simply want to configure your bash session, .bashrc would be the best choice.

Related Solutions

Bash – Populate PS1 asynchronously

re: your solution of a loop every second: you could write to a file in /tmp, instead of in your home directory. And PS1=$(customW)$(< ~/.ps1)\$ ' would save a fork/exec of cat.

re: the original question: how to get an async update to PS1: To start an async write to PS1:

set PROMPT_COMMAND to a function that checks if the data is available.
- If it is, update PS1 and unset PROMPT_COMMAND
- If not, leave PS1 with the old or placeholder value.

Use a file in /tmp for the async IO to write to, and PROMPT_COMMAND to read from.

I think this should work.

Bash !! Command – How It Works

!! is listed in the bash manual under the heading "Event Designators":

   An event designator is a reference to a command line  entry  in  the
   history list.  Unless the reference is absolute, events are relative
   to the current position in the history list.

   !      Start a history  substitution,  except  when  followed  by  a
          blank,  newline,  carriage  return,  = or ( (when the extglob
          shell option is enabled using the shopt builtin).
   !n     Refer to command line n.
   !-n    Refer to the current command minus n.
   !!     Refer to the previous command.  This is a synonym for  `!-1'.
   !string
          Refer  to the most recent command preceding the current posi-
          tion in the history list starting with string.
   !?string[?]
          Refer to the most recent command preceding the current  posi-
          tion  in  the history list containing string.  The trailing ?
          may be omitted if string is followed immediately  by  a  new-
          line.
   ^string1^string2^
          Quick  substitution.   Repeat the previous command, replacing
          string1       with       string2.        Equivalent        to
          ``!!:s/string1/string2/'' (see Modifiers below).
   !#     The entire command line typed so far.

So !! will be replaced with the previous command.

Note that the shell history will not contain the literal !! but instead the actual command that was executed:

$ ls
[some output]

$ !! .
[same output]

$ history 3
  645  2016-08-25 17:40:55 ls
  646  2016-08-25 17:40:57 ls .
  647  2016-08-25 17:41:00 history 3

Best Answer

Related Solutions

Bash – Populate PS1 asynchronously

Bash !! Command – How It Works

Related Question